CODEWITHSUNDEEP
javarot13
Regex Rookie
Regex Rookie

Reputation: 10662

ROT-13 function in java?

Is there already a rot13() and unrot13() implementation as part of one of the standard Java libraries? Or do I have to write it myself and "reinvent the wheel"?

It might look something like this:

int rot13 ( int c ) { 
  if ( (c >= 'A') && (c <= 'Z') ) 
    c=(((c-'A')+13)%26)+'A';

  if ( (c >= 'a') && (c <= 'z') )
    c=(((c-'a')+13)%26)+'a';

  return c; 
}

Upvotes: 20

Views: 32134

Answers (6)

Rishabh Gupta
Rishabh Gupta

Reputation: 1

public static String rot13(String message) {
     String a  = "";
     
     for(int i =0; i<message.length(); i++){
       if(message.charAt(i)>=65 && message.charAt(i)<=77 ||
          message.charAt(i)>=97 && message.charAt(i)<=109 ){
         a +=  (char)(message.charAt(i)+13);
         
       }
      
       else if(message.charAt(i)>=78 && message.charAt(i)<=90||
          message.charAt(i)>=110 && message.charAt(i)<=122 ){
         a +=  (char)(message.charAt(i)-13);
         
       }
         else {
           a +=  (char)(message.charAt(i));
         }
       
       
       
     }
     
     return a;
   }

Upvotes: 0

gokul656
gokul656

Reputation: 313

Sometimes inputs might have special characters, so it's better to include them.

    String input = "Do you have any cat pictures?";
    StringBuilder op = new StringBuilder();

    for (int i = 0; i < input.length(); i++) {
        char c = input.charAt(i);

        if (c == ' ') {
            op.append(" ");
        } else if (c >= 'a' && c <= 'z') {
            if (c > 'm') c -= 13;
            else c += 13;
            op.append(c);
        } else if (c >= 'A' && c <= 'Z') {
            if (c > 'M') c -= 13;
            else c += 13;
            op.append(c);
        } else {
            op.append(c);
        }
    }

Upvotes: 0

user16123931
user16123931

Reputation: 

private final static List<String> upperAlphabets = Arrays.asList(
        "A", "B", "C", "D", "E", "F", "G",
        "H", "I", "J", "K", "L", "M", "N",
        "O", "P", "Q", "R", "S", "T", "U",
        "V", "W", "X", "Y", "Z");
private final static List<String> lowerAlphabets = Arrays.asList(
        "a", "b", "c", "d", "e", "f", "g",
        "h", "i", "j", "k", "l", "m", "n",
        "o", "p", "q", "r", "s", "t", "u",
        "v", "w", "x", "y", "z");

 private static void rot(int toSkip, String value) {
        StringBuilder sb = new StringBuilder();
        int pos = 0, newPos = 0;
        boolean upper;
        for (char c : value.toCharArray()) {
            pos = upperAlphabets.indexOf(String.valueOf(c));
            if (pos == -1) {
                pos = lowerAlphabets.indexOf(String.valueOf(c));
                upper = false;
            } else {
                upper = true;
            }

            if (pos + toSkip > 25) {
                newPos = (pos + toSkip) % 26;
            } else {
                newPos = pos + toSkip;
            }

            if (upper) {
                sb.append(upperAlphabets.get(newPos));
            } else {
                sb.append(lowerAlphabets.get(newPos));
            }
        }
        System.out.println(sb);
    }

This is not only about rot13, this can do rot100 or rot1213 anything depending upon what value you are passing and the most important thing is that both list of upper case and lower case alphabets are must.

Upvotes: 1

Mr Good
Mr Good

Reputation: 1

you be doing like dis:

pblic class Rot13 {

pblic static void main(Strng[] args) {
    String s = args[0];
    for (int i = 0; i < s.length(); i++) {
        char c = s.chrAt(i);
        if       (c >= 'a' & c <= 'm') c += 13;
        els if  (c >= 'A' & c <= 'M') c += 13;
        els if  (c >= 'n' & c <= 'z') c -= 13;
        els if  (c >= 'N' & c <= 'Z') c -= 13;
        System.out.print(c);
    }
    System.out.println();
}

Upvotes: -1

Chris Thompson
Chris Thompson

Reputation: 35598

I don't think it's part of Java by default, but here's an example of how you can implement it;

public class Rot13 { 

    public static void main(String[] args) {
        String s = args[0];
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if       (c >= 'a' && c <= 'm') c += 13;
            else if  (c >= 'A' && c <= 'M') c += 13;
            else if  (c >= 'n' && c <= 'z') c -= 13;
            else if  (c >= 'N' && c <= 'Z') c -= 13;
            System.out.print(c);
        }
        System.out.println();
    }

}

Source: http://introcs.cs.princeton.edu/java/31datatype/Rot13.java.html

Upvotes: 21

georgiecasey
georgiecasey

Reputation: 23381

Might as well contribute my function to save other developers the valuable seconds

public static String rot13(String input) {
   StringBuilder sb = new StringBuilder();
   for (int i = 0; i < input.length(); i++) {
       char c = input.charAt(i);
       if       (c >= 'a' && c <= 'm') c += 13;
       else if  (c >= 'A' && c <= 'M') c += 13;
       else if  (c >= 'n' && c <= 'z') c -= 13;
       else if  (c >= 'N' && c <= 'Z') c -= 13;
       sb.append(c);
   }
   return sb.toString();
}

Upvotes: 30

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